US President Barack Obama (here addressing a joint session of Congress in 2011) is hearing a range of opinions about how to handle relations with Iran. Photo: AFP

(VOVworld) - Disagreement between the US Congress and the White House over Iran’s nuclear program has escalated. Members of both the US Senate and US House of Representatives have sent messages to the President asking for a tougher stance on Iran. This development has come since the 5 permanent UN Security Council members and Germany began talks with Iran in Vienna. According to letters from 83 out of 100 Senators, Iran still refuses to give up its uranium enrichment, which was supposed to be the top priority. The Senators want Iran to shut down its 2 heavy water reactors in Arak and Tehran and answer questions about whether Iran is using its nuclear programs for military purpose. 394 out of 435 members of the US House of Representatives signed a letter expressing their concern about Tehran’s attempt to lengthen the negotiation process to boost its oil exports.